Impairment of retrograde neuronal transport in oxaliplatin-induced neuropathy demonstrated by molecular imaging

• Published in: PloS one Vol. 7; no. 9; p. e45776
• Main Authors: Schellingerhout, Dawid, LeRoux, Lucia G, Hobbs, Brian P, Bredow, Sebastian
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 20.09.2012; Public Library of Science (PLoS)
• Subjects: Animals; Antineoplastic Agents - toxicity; Axonal transport; Biological Transport; Biology; Brain research; Cancer therapies; Chemotherapy; Clinical trials; Cold; Complications and side effects; Development and progression; Dextrose; Divergence; Fluorescence; Fluorescent Dyes - pharmacokinetics; Fluorescent indicators; Fluoroscopic imaging; Genetic aspects; Growth factors; Histology; Hypotheses; In vivo methods and tests; Medical imaging; Medicine; Mice; Mice, Inbred BALB C; Muscles; Neuroimaging; Neurons - drug effects; Neurons - metabolism; Neuropathy; Neurotoxicity; Organoplatinum Compounds - toxicity; Oxaliplatin; Pain; Peptide Fragments - pharmacokinetics; Peripheral nerve diseases; Peripheral Nervous System Diseases - chemically induced; Peripheral Nervous System Diseases - diagnosis; Peripheral Nervous System Diseases - metabolism; Regression analysis; Regression models; Rodents; Spinal cord; Spinal Cord - drug effects; Spinal Cord - metabolism; Spinal Cord - pathology; Spine; Spine (thoracic); Statistical analysis; Studies; Tetanus; Tetanus toxin; Tetanus Toxin - pharmacokinetics; Thoracic Vertebrae - metabolism; Thoracic Vertebrae - pathology; Tissues; Transport; Whole Body Imaging; United States; United States > US; Texas
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0045776

The purpose of our study was to utilize a molecular imaging technology based on the retrograde axonal transport mechanism (neurography), to determine if oxaliplatin-induced neurotoxicity affects retrograde axonal transport in an animal model. Mice (n = 8/group) were injected with a cumulative dose of 30 mg/kg oxaliplatin (sufficient to induce neurotoxicity) or dextrose control injections. Intramuscular injections of Tetanus Toxin C-fragment (TTc) labeled with Alexa 790 fluorescent dye were done (15 ug/20 uL) in the left calf muscles, and in vivo fluorescent imaging performed (0-60 min) at baseline, and then weekly for 5 weeks, followed by 2-weekly imaging out to 9 weeks. Tissues were harvested for immunohistochemical analysis. With sham treatment, TTc transport causes fluorescent signal intensity over the thoracic spine to increase from 0 to 60 minutes after injection. On average, fluorescence signal increased 722%+/-117% (Mean+/-SD) from 0 to 60 minutes. Oxaliplatin treated animals had comparable transport at baseline (787%+/-140%), but transport rapidly decreased through the course of the study, falling to 363%+/-88%, 269%+/-96%, 191%+/-58%, 121%+/-39%, 75%+/-21% with each successive week and stabilizing around 57% (+/-15%) at 7 weeks. Statistically significant divergence occurred at approximately 3 weeks (p≤0.05, linear mixed-effects regression model). Quantitative immuno-fluorescence histology with a constant cutoff threshold showed reduced TTc in the spinal cord at 7 weeks for treated animals versus controls (5.2 Arbitrary Units +/-0.52 vs 7.1 AU +/-1.38, p<0.0004, T-test). There was no significant difference in neural cell mass between the two groups as shown with NeuN staining (10.2+/-1.21 vs 10.5 AU +/-1.53, p>0.56, T-test). We show-for the first time to our knowledge-that neurographic in vivo molecular imaging can demonstrate imaging changes in a model of oxaliplatin-induced neuropathy. Impaired retrograde neural transport is suggested to be an important part of the pathophysiology of oxaliplatin-induced neuropathy.